1. Field of the Invention.
The present invention relates to prosthetic devices and, more particularly, to prosthetic foot and leg devices.
2. Prior Art.
Various types of foot and leg prosthetic devices are well known in the prior art. Such devices generally include some form of attachment for coupling the device to the dorsal end of the limb and for extending to the ground to provide body support.
Such prosthetic devices, particularly those intended to mount below the knees, are now frequently fabricated as an assembly having a leg portion and a footlike portion, with some form of pivot therebetween so as to allow the foot portion to assume various angles with the leg portion, and vice versa, as the wearer walks or goes through conventional motions. Devices of this general type are shown in U.S. Pat. Nos. 2,379,538, 3,400,408, 4,007,496, 4,089,072 and 4,161,042.
Some such prosthetic devices also include some rotatability between the foot portion and the connection to the limb, such as the ball joint of U.S. Pat. No. 3,400,408 and the swivel joint of U.S. Pat. No. 4,186,449. In general, the leg and foot portions are usually rigid members, though frequently elastic energy-absorbing members are also included to help absorb shock and for such other purposes as encouraging the ankle joint to a preferred position.
Also relevant are the teachings of my U.S. Pat. No. 4,547,913, which discloses a prosthesis characterized by the utilization of high-strength fibers and a basically unitary construction. Relevant to the continuation-in-part device are the teachings of McFarland in U.S. Pat. Nos. 1,128,018 of an articulated heel and forward portion of a foot prosthesis; Brown, 4,397,048, showing an artificial limb component fabricated from carbon fiber woven sheets; and Eyre, 4,395,783, showing the utilization of a plurality of preformed modular shin members adapted to cooperate with an identical knee support member and ankle attachment member, but differing in length of the shin tube.
Also, various methods of attachment of a prosthetic device to the end of the limb are well known, the exact manner of attachment normally depending upon exactly where the limb has been severed and the surgical technique used to close the wound. In particular, some surgical techniques result in a limb end which is particularly sensitive and, accordingly, the proper fitting of a prosthetic device to such a limb requires both careful fitting and padding.
Other techniques result in a limb end of relatively low sensitivity, allowing somewhat less of a custom fit of the prosthetic device to the limb. In any event, normally the prosthetic device is strapped to the limb to keep the prosthetic device in place throughout the wearer's normal motion, particularly when lifting the limb for walking and the like.
Because of the relatively high weight of prior art prosthetic devices in comparison to the present invention, prior art devices require tighter strapping of the device to the limb, frequently restricting the blood flow in the limb. Generally speaking, because of the weight of prior art prosthetic devices and the fact that such devices are relatively stiff and if deflectable at all, are generally deflectable in an energy-absorbing manner, the range of allowable activities of a wearer of prior art devices is generally limited to relatively slow non-strenuous activities, such as walking, etc.
More strenuous activity, such as playing tennis and other sports, running, etc., is highly limited, as the weight of the prosthetic device, the shock of the device coming down on a hard surface and the inability of the prosthetic device to return the energy absorbed therein makes the more strenuous activities with such devices either impossible or uncomfortable and awkward
Although the prior art teaches, for example, in Eyre '783, the concept of utilizing modular components in conjunction with thigh and ankle attachments, so that different shin lengths of prostheses may be supplied, there is no teaching of the concept, disclosed hereinbelow, of a single modular pylon adapted to be cut to accommodate lower leg portions of different lengths without the necessity of providing different modules.
Moreover, prior leg prostheses have, with the exception of that disclosed in my previously issued patent, been characterized by undue rigidity, mechanical-like action and difficulty of fitting to the limb of the person for whom the prosthesis is intended.